Not applicable
This invention relates to therapeutic compositions in which a cytostatic or cytocidal compound, such as a polyamine analog or a quinone, is conjugated to a polypeptide recognized and cleaved by enzymes such as prostate specific antigen (PSA) and cathepsin B. This invention also relates to medicinal uses of these conjugates, such as uses in treating cancer, and uses in treating prostate diseases such as prostate cancer, prostatitis and benign prostatic hyperplasia (BPH).
Despite advances in early diagnosis, prostate cancer remains a disease with high and increasing annual incidence and mortality. Prostate cancer is now the most frequently diagnosed cancer in men. This cancer is often latent; many men carry prostate cancer cells without overt signs of disease. Autopsies of individuals dying of other causes show prostate cancer cells in 30% of men at age 50; by age 80, the prevalence is 60%. Further, prostate cancer can take up to 10 years to kill the patient after initial diagnosis. Prostate cancer is newly diagnosed in over 180,000 men in the U.S. each year, of which over 39,000 will die of the disease. In early stage cancers, metastasis occurs to lymph nodes. In late stage, metastasis to bone is common and often associated with uncontrollable pain.
In addition to cancer, two other significant diseases of the prostate are BPH and prostatitis. The cost of treating these three diseases is immense. The annual treatment of prostatic diseases in the U.S. requires about 4.4 million physician visits and 850,000 hospitalizations, and costs billions of dollars. Although treatments for prostatic diseases exist, these are generally only partially or temporarily effective and/or produce unacceptable side effects.
Benign prostatic hyperplasia (BPH) causes urinary obstruction, resulting in urinary incontinence. It occurs in almost 80% of men by the age of 80. BPH is often treated surgically with a transurethral resection of the prostate (TURP). This procedure is very common: 500,000 TURPs are performed in the U.S. each year and BPH is the second most common cause of surgery in males. Unfortunately, a side-effect of TURP is the elimination of the ejaculatory ducts and the nerve bundles of the penis, resulting in impotence in 90% of patients.
An alternative therapy for prostate cancer involves radiation therapy. A catheter has been developed which squeezes prostate tissue during microwave irradiation; this increases the therapeutic temperature to which the prostate tissue more distal to the microwave antennae can be heated without excessively heating nearby non-prostate tissue. U.S. Pat. No. 5,007,437. A combination of a radiating energy device integrated with a urinary drainage Foley type catheter has also been developed. U.S. Pat. No. 5,344,435. However, cancerous prostatic cells generally demonstrate a slow growth rate; few cancer cells are actively dividing at any one time. As a result, prostate cancer is generally resistant to radiation therapy.
This slow growth rate also makes prostate cancer resistant to chemotherapy, although several such methods are now in use or in development. Pharmacotherapy for the treatment of BPH is currently aimed at relaxing prostate smooth muscle (alpha, blockade) and decreasing prostate volume (androgen suppression). Clinical trials have been undertaken to evaluate selective alpha, blockers, antiandrogens, and 5-alpha reductase inhibitors for the treatment of BPH. Finasteride, a 5-alpha reductase inhibitor, has shown an ability to cause regression of the hyperplastic prostate gland in a majority of patients. Mocellini et. al. (1993) Prostate 22:291; and Marberger (1998) Urology 51:677-86.
Additional therapeutic techniques for prostate cancer include using chemical forms of medical castration by shutting down androgen production in the testes, or directly blocking androgen production in the prostate. For the treatment of prostate cancer oral estrogens and luteinizing releasing hormone analogs are used as well as surgical removal of glands that produce androgens (orchiectomy or adrenalectomy). However, estrogens are no longer recommended because of serious, even lethal, cardiovascular complications. Luteinizing hormone releasing hormone (LHRH) analogs are used instead. However, hormonal therapy invariably fails with time with the development of hormone-resistant tumor cells. Furthermore, since 20% of patients fail to respond to hormonal therapy, it is believed that hormone-resistant cells are present at the onset of therapy.
Estramustine, a steroidal nitrogen mustard derivative, was originally thought to be suitable for targeted drug delivery through conjugation of estrogen to toxic nitrogen mustard. Clinical trials, however, have been disappointing when survival is used as an endpoint. Finasteride, a 4-aza steroid (Proscar(copyright) from Merck and Co.), inhibits the enzyme responsible for the intracellular conversion of testosterone to dihydrotestosterone, the most potent androgen in the prostate. Casodex(copyright) (bicalutamide, Zeneca, Ltd.), a non-steroidal anti-androgen, is thought to inhibit cellular uptake of testosterone by blocking androgen receptors in the nucleus. However, almost all advanced cancer prostate cells fail to respond to androgen deprivation.
An additional method for treating prostatic diseases involves administration of inhibitors of polyamine synthesis. Dunzendorfer (1985) Urol. Int. 40:241-250. Naturally-produced polyamines include spermidine and spermine and their precursor, diamine putrescine, which are secreted by the prostate gland and are abundant in the seminal fluid. Polyamines are required for cell division, and probably for differentiation. Spermine apparently stabilizes the DNA, which is tightly packed in the heads of sperm cells. Polyamines may be essential for stability of actin filament bundles and microtubules. However, polyamine biosynthesis inhibitors such as alpha-difluoromethylornithine (DFMO) cause toxicities, including severe hearing loss, these toxicities sometimes forcing the cessation of treatment. Splinter et al. (1986) Eur. J. Cancer Clin. Oncol. 22:61-67; and Horn et al. (1987) Eur. J. Cancer Clin. Oncol. 23:1103-1107. Another inhibitor, methylglyoxal-bis-guanylhydrazone (MGBG), caused side effects so extreme that, in one study, drug deaths occurred in over half of treated animals. Dunzendorfer (1985); and Herr et al. (1984) Cancer 53:1294-1298.
A related type of therapy for prostate cancer involves using polyamine analogs, such as DENSPM (N1,N11-diethylnorspermine or BE-333). Mi et al. (1988) Prostate 34:51-60. While the precise role(s) of naturally-produced polyamines have not been clearly defined, interactions with DNA and RNA have been convincingly implicated. Since the nature of these interactions is highly structure-dependent, polyamine analogs have been designed to effectively disrupt polyamine function by competition with naturally-occurring polyamines. Several polyamine analogs have been developed that exert marked inhibition of human tumor cell growth both in culture and in nude mice xenografts. Polyamine analogs such as BE-4444 [1,19-bis(ethylamino)-5,10,15-triazanonadecane], BE-373 [N,Nxe2x80x2-bis(3-ethylamino)propyl)-1,7-heptane diamine], and BE-333 are particularly effective in inhibiting prostate xenograft tumors in nude mice. Zagaja et al. (1998) Cancer Chem. Pharm. 41:505-512; Jeffers et al. (1997) Cancer Chem. Pharm. 40:172-179; Feuerstein et al. (1991) J. Cell. Biochem. 46:37-47; and Marton et al. (1995) Ann. Rev. Pharm. Toxicol. 35:55-91. However, polyamine analogs can cause systemic toxicity. BE-333, for example, causes side effects such as headache, nausea and vomiting, unilateral weakness, dysphagia, dysarthria, numbness, paresthesias, and ataxia. Creaven et al. (1997) Invest. New Drugs 15:227-34. In one test, administration of BE-333 caused labored breathing, convulsive movements and acute death in rats. Kanter et al. (1994) Anticancer Drugs 5:448-56. This toxicity limits many polyamine analogs to a small therapeutic window.
None of the above techniques for treating prostate diseases has been universally successful. Following localized therapy, up to 40% of patients with advanced disease, and a large proportion of all patients, eventually develop metastatic disease. Treatment for advanced disease initially involving hormonal manipulations and palliative radiotherapy have demonstrated symptomatic relief, but not long-term disease-free survival. The use of cytotoxic agents in the management of hormone-resistant advanced prostate cancer remains poorly defined. A few single agents have become xe2x80x9cstandard therapyxe2x80x9d, although demonstration of their efficacy, by contemporary standards, is lacking. Combinational chemotherapy is frequently employed, although its contribution to overall patient management is largely unsubstantiated, especially when critical assessment of efficacy parameters are used. Newer approaches using chemohormonal therapy and hormonal priming therapies have failed. High-dose chemotherapy with transplant regimens are not well-tolerated in an elderly population, to which most victims of prostate cancer belong. A growth factor inhibitor, suramin, has shown promising initial results, but also many side effects. Allolio et al. (1989) Dtsch. Med. Woschenschr. 114:381-4; and Broder et al. (1985) Lancet 2:627-30. However, no therapy to date has been demonstrated to improve overall survival in patients with advanced hormone refractory prostate cancer.
Approximately one out of every four males above the age of 55 suffers from a prostate disease. Due to the aging U.S. population, the incidence of BPH, prostatitis and prostate cancer is likely to increase and to become an even more severe problem.
It would be advantageous to develop a new treatment of prostate cancer which retains the potency of chemotherapy without being subject to the various side effects and disadvantages of current therapies.
All references cited herein are hereby incorporated by reference in their entirety.
The invention provides therapeutic compositions in which a cytostatic or cytocidal agent is conjugated to a polypeptide, where the polypeptide is cleaved from the agent by an enzyme.
In one embodiment, the cytostatic or cytocidal agent is a polyamine analog. The polyamine analog can be linked to the peptide at the carboxy terminus of the peptide by an amide linkage to a primary or secondary amine group of the polyamine. The polyamine analog can contain a hydroxy group, and can be linked to the peptide at the carboxy terminus of the peptide by an ester linkage through the hydroxy group. In another embodiment, the polyamine analog is conformationally restricted.
In another embodiment of the invention, the polyamine analog linked to the polypeptide is of the formula:
xe2x80x94N(xe2x80x94E)xe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94E
or
xe2x80x94HNxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94E
wherein each A is independently selected from the group consisting of a single bond, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; each B is independently selected from the group consisting of: a single bond, C1-C6 alkyl, and C2-C6 alkenyl; and each E is independently selected from the group consisting of H, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; and any salt or stereoisomer thereof.
In another embodiment of the invention, the polyamine analog linked to the polypeptide is of the formula:
xe2x80x94N(xe2x80x94E)xe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94E
or
xe2x80x94HNxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94E
wherein each A is independently selected from the group consisting of a single bond, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; each B is independently selected from the group consisting of: a single bond, C1-C6 alkyl, and C2-C6 alkenyl; and each E is independently selected from the group consisting of H, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; with the proviso that either at least one A moiety is selected from the group consisting of C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl, or at least one B moiety is selected from the group consisting of C2-C6 alkenyl; and any salt or stereoisomer thereof.
In another embodiment of the invention, the polyamine analog linked to the polypeptide is of the formula:
xe2x80x94N(xe2x80x94E)xe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NH(xe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NH)xxe2x80x94E
or
xe2x80x94HNxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NH(xe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NH)xxe2x80x94E
wherein each A is independently selected from the group consisting of: a single bond, C6-C2 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; each B is independently selected from the group consisting of: a single bond, C1-C6 alkyl, and C2-C6 alkenyl; each E is independently selected from the group consisting of H, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; and x is an integer from 2 to 16; and any salt or stereoisomer thereof.
In another embodiment of the invention, the polyamine analog linked to the polypeptide is of the formula:
xe2x80x94N(xe2x80x94E)xe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NH(xe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NH)xxe2x80x94E
or
xe2x80x94HNxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NH(xe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NH)xxe2x80x94E
wherein each A is independently selected from the group consisting of: a single bond, C6-C2 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; each B is independently selected from the group consisting of: a single bond, C1-C6 alkyl, and C2-C6 alkenyl; each E is independently selected from the group consisting of H, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; and x is an integer from 2 to 16; with the proviso that either at least one A moiety is selected from the group consisting of C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl, or at least one B moiety is selected from the group consisting of C2-C6 alkenyl; and any salt or stereoisomer thereof.
In another embodiment of the invention, the polyamine analog linked to the polypeptide is of the formula:
Exe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NH(xe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NH)xxe2x80x94E
wherein each A is independently selected from the group consisting of: a single bond, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; each B is independently selected from the group consisting of: a single bond, C1-C6 alkyl, and C2-C6 alkenyl; each E is independently selected from the group consisting of C1-C6 alkyl, C1-C6 alkanol, C3-C6 cycloalkanol, and C3-C6 hydroxyaryl, and the peptide is linked to the polyamine via an ester linkage at one and only one E group hydroxy; and x is an integer from 0 to 16; and any salt or stereoisomer thereof.
In another embodiment of the invention, the polyamine analog linked to the polypeptide is of the formula:
Exe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NH(xe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NH)xxe2x80x94E
wherein each A is independently selected from the group consisting of: a single bond, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; each B is independently selected from the group consisting of: a single bond, C1-C6 alkyl, and C2-C6 alkenyl; each E is independently selected from the group consisting of C1-C6 alkyl, C1-C6 alkanol, C3-C6 cycloalkanol, and C3-C6 hydroxyaryl, with the proviso that at least one E moiety be selected from the group consisting of C1-C6 alkanol, C3-C6 cycloalkanol, and C3-C6 hydroxyaryl, and the peptide is linked to the polyamine via an ester linkage at one and only one E group hydroxy; and x is an integer from 0 to 16; and any salt or stereoisomer thereof.
In another embodiment of the invention, the polyamine analog linked to the polypeptide is of the formula:
xe2x80x94N(xe2x80x94E)xe2x80x94Dxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Dxe2x80x94NHxe2x80x94E
or
xe2x80x94NHxe2x80x94Dxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Dxe2x80x94NHxe2x80x94E
wherein A is selected from the group consisting of C2-C6 alkynyl; each B is independently selected from the group consisting of: a single bond, C1-C6 alkyl, and C2-C6 alkenyl; each D is independently selected from the group consisting of C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloalkenyl, and C3-C6 cycloaryl; and each E is independently selected from the group consisting of H, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; and any salt or stereoisomer thereof.
In another embodiment of the invention, the polyamine analog linked to the polypeptide is of the formula:
xe2x80x94N(xe2x80x94E)xe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Fxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94E
or
xe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Fxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94E
wherein F is selected from the group consisting of C1-C6 alkyl; each A is independently selected from the group consisting of: a single bond, C1-C6 alkyl; C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; each B is independently selected from the group consisting of: a single bond, C1-C6 alkyl, and C2-C6 alkenyl; and each E is independently selected from the group consisting of H, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; and any salt or stereoisomer thereof.
In another embodiment of the invention, the polyamine analog linked to the polypeptide is of the formula:
xe2x80x94N(xe2x80x94E)xe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Fxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94E
or
xe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94Fxe2x80x94NHxe2x80x94Bxe2x80x94Axe2x80x94Bxe2x80x94NHxe2x80x94E
wherein F is selected from the group consisting of C1-C6 alkyl; each A is independently selected from the group consisting of: a single bond, C1-C6 alkyl; C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; each B is independently selected from the group consisting of: a single bond, C1-C6 alkyl, and C2-C6 alkenyl; and each E is independently selected from the group consisting of H, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl; with the proviso that either at least one A moiety is selected from the group consisting of C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C3-C6 cycloaryl, and C3-C6 cycloalkenyl, or at least one B moiety is selected from the group consisting of C2-C6 alkenyl; and any salt or stereoisomer thereof.
In another embodiment, the cytostatic or cytocidal agent is a quinone, such as a naphthoquinone. In one embodiment, the naphthoquinone contains a hydroxy group and is linked to the peptide by the hydroxy group. In another embodiment, the naphthoquinone contains a primary or secondary amino group and is linked to the peptide by the amino group.
In another embodiment of the invention, the quinone linked to the polypeptide is selected from compounds of the formula 
wherein A is xe2x80x94CH2xe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94C(xe2x95x90O)xe2x80x94Oxe2x80x94, or xe2x80x94Oxe2x80x94C(xe2x95x90O)xe2x80x94, and M1 is C1-C8 alkyl, C1-C8 branched alkyl, C3-C8 cycloalkyl, or C3-C8 cycloaryl.
In another embodiment of the invention, the quinone linked to the polypeptide is selected from compounds of the formula 
wherein x is 1 or 2; and each K is independently selected from the group consisting of H, OH, C1-C8 alkyl, C1-C8 alkenyl, C1-C8 alkanol, C1-C8 alkoxy, and 
with the proviso that one and only one K is selected from the group consisting of OH and C1-C8 alkanol, the peptide being conjugated to the terminal hydroxy group of the alcohol; and where zero or two, but no more than two, vicinal K""s in the molecule represent single electrons which form a pi bond, thus forming a double bond together with the existing sigma bond between the two adjacent carbons bearing the two vicinal K""s.
In another embodiment of the invention, the quinone linked to the polypeptide is selected from compounds of the formula 
wherein Y is selected from the group consisting of xe2x80x94H, xe2x80x94F, xe2x80x94Br, xe2x80x94Cl, and xe2x80x94I; and wherein G1 is selected from the group consisting of H, C1-C8 alkyl, 
and xe2x80x94C(xe2x95x90O)xe2x80x94CHnX3xe2x88x92n, where n is an integer from 0 to 3 and X is selected from the group consisting of F, Cl, Br, and I; and the peptide is conjugated to the quinone via the amino group bearing G1.
In another embodiment of the invention, the quinone linked to the polypeptide is selected from compounds of the formula 
wherein x is 1 or 2; and each K is independently selected from the group consisting of H, C1-C8 alkyl, C1-C8 alkenyl, C1-C8 alkoxy, and 
and where zero or two, but no more than two, vicinal K""s in the molecule represent single electrons which form a pi bond, thus forming a double bond together with the existing sigma bond between the two adjacent carbons bearing the two vicinal K""s.
In one embodiment of the invention, the cytostatic or cytocidal agent is conjugated to a polypeptide recognized and cleaved by prostate-specific antigen (PSA). In one embodiment, the polypeptide is recognized and cleaved by PSA and comprises less than about 25 amino acids. Preferably, the polypeptide comprises less than about 10 amino acids. More preferably, the polypeptide comprises the sequence HSSKLQ (SEQ ID NO:1). More preferably, the polypeptide comprises or consists of the sequence SKLQ-xcex2-alanine (SEQ ID NO:2) or SKLQL, (SEQ ID NO:3) or comprises or consists of the sequence SKLQ (SEQ ID NO:4).
In another embodiment, the cytostatic or cytocidal agent is conjugated to a polypeptide recognized and cleaved by cathepsin B. In one embodiment, the peptide sequence is X-P2-P1, where X is hydrogen, an amino-protecting group, or an amino-capping group attached to the N-terminus of P2; where P2 is the N-terminal amino acid and P1 is the C-terminal amino acid; and where P2 is a hydrophobic amino acid and P1 is a basic or polar amino acid. In another embodiment, the peptide sequence is X-P2-P1-Y, where X is hydrogen, an amino-protecting group, or an amino-capping group attached to the N-terminus of P2; P2 is a hydrophobic amino acid; P1 is a basic or polar amino acid; and where Y is leucine, xcex2-alanine, or a nonentity. In a further embodiment, X is a 4-morpholinocarbonyl group. In yet another embodiment, P2 is selected from the group consisting of leucine, isoleucine, valine, methionine, and phenylalanine; and P1 is selected from the group consisting of lysine, arginine, glutamine, asparagine, histidine and citrulline.
The invention also comprises compositions where the cytostatic or cytocidal agent conjugated to a polypeptide is combined with a pharmaceutically acceptable excipient.
The invention also provides methods of treating cancers and other diseases characterized by cell proliferation, for example prostate cancer, in an individual comprising administering to the individual an effective amount of a composition comprising a therapeutic amount of a cytostatic or cytocidal agent conjugated to a polypeptide. These conjugates include polyamine analog conjugates or quinone conjugates of the present invention, for example, a polyamine analog or a quinone conjugated to a polypeptide recognized and cleaved by an enzyme such as prostate-specific antigen (PSA) or cathepsin B. The disease can be prostatitis, benign prostate hyperplasia (BPH), or prostate cancer, and can include suppression of the proliferation of metastatic tumors. The individual can be a mammal, and is preferably a human.